The increasing attention towards energy efficiency issues has triggered an important process involving the renovation of existing buildings and, at the same time, the creation of recognized certifications assuring the quality of the projects. In line with this trend, the Sweco headquarters, an office building characterized by 24700 m2 of floor area and located in Stockholm, was totally retrofitted in 2012 and obtained the Gold rating after being assessed with the Miljöbyggnad certification procedure. The HVAC system was a key element of the retrofit project since one of the final aims was to combine high indoor environment standards with efficient system performances. However, even if the quality of the design is certified, it is possible that, under real operating conditions, complex systems behave differently from the expectations and adjustments are necessary to correct the emerged gap. To achieve this goal, it is essential to identify the points of weakness of the system by carrying out an energy performance analysis, which is the core of this project. In fact, after providing an overview of the building and the retrofit, this work focuses on the analysis of the cooling system installed in the Sweco building and proves the importance of adopting a step-by-step approach to the problem. Therefore, an increasing level of detail characterizes each step of the analysis, whose final aim is to highlight potential aspects to be improved and create a baseline to test possible solutions. / SIRen

The hygrothermal analysis of building envelopes plays a crucial role in the renovation strategies for historical buildings. Dynamical hygrothermal simulations under realistic conditions are effective in predicting moisture-related damages, including the risk of mold growth or frost damage, which can arise when combining historical walls with modern insulation systems. However, accurately modeling and simulating historic walls, composed of brick/stone and mortar joints, using detailed two- or three-dimensional models, is a complex and time-consuming task. As a result, a common practice in hygrothermal simulations is to simplify old masonry into a one-dimensional layer of stone/brick, disregarding mortar joints. Nonetheless, in this study cases were identified where this simplification approach leads to unacceptable inaccuracies, particularly when historic masonry is combined with vapor-tight insulation systems. Also, this study investigated the influence of the internal geometry of mortar joints and the stone/mortar ratio in hygrothermal simulations. While the internal disposition of joints showed minimal influence, the stone/mortar ratio was found to play a significant role. In light of these findings, this thesis proposes a method to replace the complex representation of historical masonry with a fictitious homogenized porous material that incorporates the influence of mortar joints. The hygrothermal properties of this newly developed ‘Homogenized Porous Material’ are averaged and optimized to closely approximate the behavior of the hygrothermal model for important applications. The proposed method was applied to various combinations of mortars, stones, and bricks. Furthermore, the behavior of the ‘Homogenized Porous Material’ was evaluated under dynamic conditions, specifically for the case of an internally insulated wall in different climates. A comparison was made with a two-dimensional fully described model to assess the performance of the developed method. The results demonstrate considerable improvements compared to the conventional one-dimensional stone/brick layer approximation, with the degree of improvement being more pronounced when the hygrothermal properties of the stone/brick and mortar differ significantly. The developed method offers significant advantages: for example, the application to 3D building energy simulation tools which entangle moisture balances, allows for quick pre-checks for moisture damage. This can help pre-assessing the potential risks of moisture-related issues in a time-efficient manner also at building component level. Moreover, in time-critical studies where a large number of variant analyses are required, 1D models remain essential as they allow for efficient sensitivity analyses with a large number of simulations runs. This method facilitates a comprehensive exploration of different scenarios and parameter variations, aiding in the identification of critical factors affecting the hygrothermal performance of historic walls. Furthermore, the developed method has potential applications in situations where the inner structure of walls is unknown, such as forensic analysis of historical constructions. By providing a reliable and simplified representation of the hygrothermal behavior, this method can support investigations and assessments of moisture-related issues in historical buildings, even when detailed knowledge of the internal structure is limited. In conclusion, this research can offer to architects and engineers practical benefits in terms of accurate prediction of moisture-related damages, efficient pre-checks, sensitivity analyses, and applications in cases with limited knowledge of wall structures. In future, an extended database of ‘Homogenized Porous Materials’, suitable to model masonry walls, can be built for the users.:Preface Abstract Kurzfassung Table of Contents Chapter 1 - Introduction and overview 1.1 Motivation 1.2 Problem statement 1.3 Thesis 1.4 Solution strategy and methodology 1.5 Structure of the study Chapter 2 - Literature background 2.1 General concepts concerning historical masonry 2.2 Theory and tool for hygrothermal simulations 2.2.1 Balance equation of energy and mass for the porous medium 2.2.2 Flux of energy and mass for the porous medium 2.2.3 Climate and boundary conditions Incident wind-driven rain Radiation, short-wave and long-wave Interior climate 2.3 Main hygrothermal properties of materials and experimental measurement procedures 2.3.1 Bulk density and porosity: helium pycnometer 2.3.2 Specific heat capacity: calorimeter 2.3.3 Thermal conductivity: the hot plate measurement 2.3.4 Vapour conductivity: the cup-tests 2.3.5 Moisture storage function: desiccator method and pressure plates 2.3.6 Liquid conductivity: water uptake and drying experiment 2.3.7 Vapor and liquid conductivity function: capillary condensation redistribution test (CCR) 2.4 Complexity and simplification for the hygrothermal modeling and simulation of historical masonry Chapter 3 - Quantifying the Impact of Mortar Joints in Hygrothermal Simulations of Historical Masonry 3.1 Investigation through dynamical hygrothermal simulation in realistic condition 3.2 Evidence of mortar joints’ impact in hygrothermal simulations of historic walls 3.3 Dependence of the hygrothermal transport of a masonry wall on its internal geometry 3.4 Discrepancies due to assumptions on stone/mortar ratio 3.5 The case of a three-dimensional simulation Chapter 4 - A fictitious ‘Homogenized Porous Material’ (HPM) to describe heat and moisture transport in a massive historic wall 4.1 Definition of the preliminary activities: choice of the reference model and of the materials 4.2 Homogenized porous material characterization 4.2.1 Phase 1: hygrothermal properties through analytical calculation Bulk density, ρ Porosity, θpor Specific heat capacity, Cp Moisture storage function, θl,HPMpc 4.2.2 Phase 2: hygrothermal properties through numerical experiment Dry Thermal conductivity, λdry Thermal conductivity function, λ(θl) Dry water vapour resistance factor, μdry Water vapour conductivity function, Kv(θl) 4.2.3 Phase 3: hygrothermal properties through optimization algorithm 4.3 Conclusions on the developed method Chapter 5 - Application of the ‘Homogenized Porous Material’ (HPM) method 5.1 Preliminary activities and reading instructions 5.2 Homogenized Porous Material characterizations in three phases 5.3 Dynamical hygrothermal simulation in realistic condition with Homogenized Porous Materials 5.3.1 Simulations set-up 5.3.2 Analyzed Output 5.3.3 Result of the simulation in realistic design condition with Interior Insulation 5.4 Discussion on the obtained results 5.4.1 Discussion on HPM calibration results 5.4.2 Discussion on HPM dynamical hygrothermal simulation in realistic condition 5.5 Conclusions on the tests Chapter 6 - Summary, conclusions and outlooks 6.1 Content summary 6.2 Achievements and conclusions 6.3 Future prospects Appendix I List of Figures (Appendix I) List of Tables (Appendix I) Appendix II List of Figures (Appendix II) Appendix III List of figure (Appendix III) List of Tables (Appendix III) List of Abbreviations and Symbols List of Figures List of Tables Acknowledgements Bibliography

The purpose of this research is to determine the average energy intensity of multi-unit residential buildings (MURBs) in Toronto, and evaluate whether certain building characteristics influence energy intensity. This information is particularly important in the Toronto market. Relative to the city’s population, Toronto has an unusually high proportion of MURBs with more than half of residential dwellings in apartment buildings. Additionally, Toronto MURBs are significant consumers of energy and produce an estimated 1.3M tonnes of CO2e each year. The ultimate goal is to assess the most efficient building retrofit measures. Energy consumption data for Toronto MURBs were collected and weather normalized. Correlations between the energy data and the building characteristics were examined. Window characteristics and heating system type were found to have the most significant influence on energy intensity. Establishing energy consumption characteristics of MURBs is the first step towards improving the energy efficiency of Toronto’s MURBs stock.

The purpose of this research is to determine the average energy intensity of multi-unit residential buildings (MURBs) in Toronto, and evaluate whether certain building characteristics influence energy intensity. This information is particularly important in the Toronto market. Relative to the city’s population, Toronto has an unusually high proportion of MURBs with more than half of residential dwellings in apartment buildings. Additionally, Toronto MURBs are significant consumers of energy and produce an estimated 1.3M tonnes of CO2e each year. The ultimate goal is to assess the most efficient building retrofit measures. Energy consumption data for Toronto MURBs were collected and weather normalized. Correlations between the energy data and the building characteristics were examined. Window characteristics and heating system type were found to have the most significant influence on energy intensity. Establishing energy consumption characteristics of MURBs is the first step towards improving the energy efficiency of Toronto’s MURBs stock.

Office retrofit building projects have become a subject of increased attention among building researchers in the United Kingdom, and in many economically advanced nations. Existing whole-life costing models have however, not proven to be robust enough to deal with these retrofit building scenarios. There is a growing body of evidence that conceptual modifications in the mechanics of whole-life cost modelling, could facilitate improvements in the long-term cost assessment of buildings. Recent research has made a case for the existence of revocability and disruption, in the appraisal of retrofit building investments. Revocability, connotes the potential for variability, in the future cost projections of a building over its estimated life. Disruption relates to the diminished building use, or unusability, over a period of implementing a retrofit initiative. Existing whole-life cost models have however, not recognised the implications of revocability and disruption in their framework. This study conducts an investigation into the whole-life costing of office retrofit building projects, and develops a Fuzzy New-Generation Whole-life Costing approach. Two office retrofit building projects are adopted, to appraise the identified issues in the whole-life costing framework. A number of building configuration permutations (BCPs) constituting different retrofit options, are developed in both projects. The potential implication of revocability and disruption, are evaluated based on probability and fuzzy logic principles respectively. Sensitivity analysis is applied to discount rate assumptions over the estimated lives, of the projects considered. The Spearman's rank correlation coefficient is used in analysing the ranking results of selected projects. This provided an assessment of the relative preference of BCPs in the projects. Results from the case studies show 1) disruption issues account for up to 12% of initial capital costs; 2) revocability accounts for up to 35% of initial capital cost, over a 20-year life; up to 119%, over a 60-year life; 3) up to 2% underestimation in the whole-life cost, over a 20-year life; and up to 45% underestimation, over a 60-year period, in the SPACE project; 4) up to 9% underestimation in the whole-life cost, over a 20-year life; and up to 53% underestimation, over a 60-year life, in the MS project.

In Sweden, a large share of residential buildings was built more than 50 years ago. Consequently, old materials, poor maintenance, and corrosion can affect the structural performance of these buildings. Additionally, these buildings do not meet the latest energy efficiency and Eurocode regulations. Building retrofits can improve structural strength and resident safety, as well as the energy efficiency of the buildings. Common retrofitting methods are unsustainable in terms of costs, duration, and disruptions to resident’s lives. A sustainable method for structural and energy upgrades is needed in order to retrofit such kind of structures in an efficient way. This master thesis aims to identify an innovative structural and energy retrofitting solution for reinforced concrete buildings that are reaching the end of their service life as well as to provide an environmental impact assessment of this whole process. A multi-family building built in 1972 in Ronneby, Sweden, with reinforced concrete load-bearing walls and slabs was considered as a case study. An integrated retrofitting strategy based on an addition of cross-laminated timber (CLT) panels, insulation, and claddings to the external walls to increase the horizontal load-bearing capacity and energy efficiency of the building was applied in this study. Steel tubes and fiber-reinforced polymers (FRP) are used to increase the load-bearing capacity of the internal load-bearing walls and slab compared to the original ones, mostly for vertical loads. For the structural analysis based on the Eurocode regulations, the software RFEM was used to model and analyze the building before and after retrofitting. In addition to that, dynamic thermal simulation was performed with VIP-Energy software to analyze the service life energy consumption before and after retrofitting of the building. Life cycle assessment following the European standard SS-EN 15978 was used to assess the environmental impacts including global warming potential (GWP), acidification potential (AP), and eutrophication potential (EP). The environmental impact of the existing building was compared with the retrofitted case, during a 50-year service life. The results show that after the retrofitting in the load-bearing walls, the internal shear forces induced by wind loads decreased by 38%. Also, the load-bearing capacity of the slabs was increased by 350% in the critical areas. Regarding GWP, AP and EP all decreased by 30% in the retrofitted case. The results indicate that by retrofitting the building, structural performance and safety increase, and moreover the environmental impact of the building is minimized.